Describe cigarette smoking abstinence among employer and health plan-sponsored quitline registrants who were not using Electronic Nicotine Delivery Systems (ENDS), were using ENDS to quit smoking or were using ENDS for other reasons at the time of quitline registration. We examined 6029 quitline callers aged ≥18 years who smoked cigarettes at registration, and completed ≥1 counselling calls, baseline ENDS use questions and a 6-month follow-up survey (response rate: 52.4%). 30-day point prevalence smoking quit rates (PPQRs) were assessed at 6-month follow-up (ENDS-only users were considered quit). Data were weighted for non-response bias. Logistic regression analyses controlled for participant characteristics and programme engagement. At registration, 13.8% of respondents used ENDS (7.9% to quit smoking, 5.9% for other reasons). 30-day PPQRs were: 55.1% for callers using ENDS to quit, 43.1% for callers using ENDS for other reasons, and 50.8% for callers not using ENDS at registration. Callers using ENDS for other reasons were less likely to quit than other groups (adjusted ORs=0.65–0.77); quit rates did not significantly differ between non-ENDS users and those using ENDS to quit. Among callers using ENDS to quit at baseline, 40% used ENDS regularly at follow-up. ENDS users not using ENDS to quit smoking were less successful at quitting at 6-month follow-up compared with callers using ENDS to quit smoking and callers who did not use ENDS at programme registration. Incorporating reasons for ENDS use may be important for future studies examining the role of ENDS in tobacco cessation.